Last week news emerged from the English Premier League that one of the stars of Arsenal FC would be out of action for a month following minor surgery on his ankle. Thomas Vermaelen wrote on his Twitter page “Yesterday I had a small procedure to take out my plantaris tendon”. Removing a tendon may sound to many like quite a serious event, they are generally essential for proper functioning of the body but not in this case. You see the plantaris tendon is a vestigial organ. In our ape ancestors the plantaris muscle was used to flex the foot to grasp like a hand; a few million years of evolution have adapted human feet for upright walking on solid ground so the flexing of a foot is no longer beneficial. Now 7-10% of people have no plantaris muscle at all (Simpson et al. 1991) and the rest of us are transitional; stuck between our tree climbing past and our road running future. Creationist thinking supposes there can be no relics from ancestral species therefore any organ in any body must be functional and necessary; if no use is currently known then they’ll eventually find one. The plantaris obviously doesn’t have a motor function so is claimed to be a ‘highly specialized sensory muscle’ crucial to fine movement control and positional awareness. Loss of these qualities would be disastrous for an elite sportsman but fortunately Thomas Vermaelen isn’t too worried, he’s already had the same operation on his other ankle.

Our bodies are littered with remnants of structures from our ancestors, probably the most famous of which is the appendix. Despite the clear connections with the caecum in other mammals creationists claim the vestigiality of the appendix has been disproved and it is a functional, necessary part of human anatomy. Darwin, they say, was wrong. They seemed to have somewhat missed the point; the existence of some of sort of current function does not negate the quality of being a vestige. Darwin made clear that: “An organ, serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose, and remain perfectly efficient for the other”. He had very little to say about the vermiform appendix but understood it to be both useless, citing the huge variability of its expression in individuals, and sometimes an actual cause of death. In 1930s America up to 20,000 people a year were killed by appendicitis and to this day US Doctors encounter over 100,000 patients a year with a perforated appendix. The developed world has now seen an enormous reduction in fatalities from appendicitis but even now to regard this organ as an example of perfect design would seem willfully ignorant at best. Anti-evolutionists are ever keen to disprove evolutionary theory by seeking functions for vestigial organs such as the appendix and after decades of speculating the current best guess is that it may act a reservoir for gut bacteria to be called into use in the event of serious illness. Creationists will cite numerous other ideas to hedge their bets even though this actually counters their own argument; one specialised and unique function would best support their cause but the appendix has never been convincingly shown to have one. If it did people without an appendix would suffer for their loss but we find a person can have their appendix removed and continue to live as they did before. Claims of some current function are an irrelevance anyway, whether or not one exists does not mean the structure isn’t derived from an ancestral form with a different or more pronounced function. The appendix is very much a vestigial organ and how ever many functions we may find for it, it will continue to be so.